Optical fibers are widely used in a variety of data transmission applications including, primarily at the present, the telecommunications industry. Because optical fibers transmit voice and other data far more rapidly and efficiently Lhan copper wire, the demand for optical fibers is continuing to increase. For example, optical fibers no longer serve merely as the medium for long distance signal transmission, but are increasingly routed directly to the home or, in some instances, directly to a desk or other work location to network computers.
In order to route and install fiber optic cable in builings or other structures, the fiber optic cable must generally be routed or pulled through a protective conduit or duct having a diameter of as little as 2 inches. Generally, a pulling grip consisting essentially of a tubular mesh with a loop at one end, such as disclosed in U.S. Pat. No. 4,368,910, is attached to the lead end of the fiber optic cable. A rope is then attached to the pulling grip for pulling the cable through the conduit.
Fiber optic cable of various diameters and wall thicknesses is now being manufactured to meet the requirements of various applications. Many fiber optic cables include one or more buffer tubes, each of which can carry a plurality of optical fibers. The optical fibers may be in a loose bundle or a ribbon form. Fiber optic cables also generally include a protective jacket which surrounds the buffer tube(s) in order to further protect the optical fibers. For added convenience, pre-connectorized fiber optic cable is also available. With pre-connectorized fiber optic cables, each of the optical fibers include a respective factory-installed connector which has been mounted on an end portion of the optical fiber prior to installation of the fiber optic cable. By mounting the connectors in the factory, the time required in the field to install and connect the fiber optic cable is reduced. In addition, the quality of the resulting connection may be enhanced by mounting the connectors in the factory since the factory conditions can be more readily controlled than the field conditions.
Presently, installing pre-connectorized fiber optic cable is fairly difficult due to the mass of connectors mounted on the ends of the optical fibers at the lead end of the fiber optic cable. For installation, the cable jacket and strength members are generally cut back a certain distance from the pre-connectorized end portions of the optical fibers. As a result, a leg length is defined for each optical fiber as the distance between the end of the cable jacket and the respective connector. The mass of connectors at the end of the optical fibers has required that the leg lengths of the fibers be staggered so that the connectors can fit within the relatively small diameter conduit or duct through which the fiber optic cable is routed. Depending upon the particular installation requirements, these staggered leg lengths may be undesirable. For example, the layout of a particular installation may require that the leg lengths be uniform in length. Additionally, other installations may require the leg lengths to vary significantly which also makes installation of the fiber optic cable difficult using present techniques and tools.
U.S. Pat. No. 5,133,583 discloses an advantageous method for using a contractile mesh pulling grip to pull a fiber optic cable through a conduit. According to this method, a portion of the cable jacket is removed to expose an end portion of the strength members which may thereafter be attached to the pulling grip. The mesh type pulling grip of U.S. Pat. No. 5,133,583 is not, however, suitable for installing pre-connectorized fiber optic cables because it does not provide suitable protection for the connectors or the optical fibers which must be protected from excessive bending during installation.
Therefore, while pulling grips and methods are presently available for installing pre-connectorized fiber optic cable, these present pulling grips and methods do not allow the installation of pre-connectorized optic fibers with uniform leg lengths or significantly varying leg lengths. Furthermore, present pulling grips do not fully protect the optical fibers or their connectorized end portions from the mechanical stress and strain to which they are subjected during installation.